Here are instructions for uninstalling Matrixrate from the database:

We accept no responsibility for errors; make a backup if unsure.

1. Go into phpmyadmin
2. Bring up sql prompt
3. Run select * from core_config_data WHERE path like “carriers/matrixrate%”;
4. Ensure values returned look correct (if in doubt be careful!)
5. Run delete FROM core_config_data WHERE path like “carriers/matrixrate%”;